Down-regulation of Th1 type of response in early human American cutaneous leishmaniasis

This study examined the T cell responses in the early phase of Leishmania b raziliensis infection. Cytokine profiles, lymphoproliferative responses, an d skin test results in 25 patients with early cutaneous leishmaniasis (ECL; illness duration <60 days) were compared with those in persons with late c utaneous leishmaniasis (LCL; illness duration >2 months). Absent or low lym phoproliferative responses were observed in 8 (32%) of 25 patients and an a bsence of interferon (IFN)-gamma production in 9 (41%) of 22 patients prior to therapy. IFN-gamma production in ECL (mean +/- SD) was lower than in LC L (293 +/- 346 vs. 747 +/- 377 pg/mL, respectively; P<.01). In contrast, in terleukin (IL)-10 production in ECL(mean +/- SD) was higher than in LCL(246 +/- 56 vs. 50 +/- 41 pg/mL, respectively; P <.01),Restoration of lymphopro liferative responses and IFN-gamma production was achieved when monoclonal antibody to IL-10 or IL-12 was added to the cultures. These results show th at T cell responses during early-phase infection are down-regulated by IL-1 0 and may facilitate parasite multiplication.